Probable reserves

Estimates of the amount of natural gas available are made within the context of definitions and are subject to revision as definitions change, as additional information becomes available, as resources are consumed, or as undedyiag assumptions are altered. These definitions iaclude proved reserves where the resource is expected to be recoverable and marketable usiag known technology and prices probable reserves where a resource has been identified but not completely characterized and possible or potential gas where estimates are based on the available geological iaformation, historical trends, and previous successes. There are variations ia these definitions throughout the world. 

Confederation of Independent States (CIS) are denoted as explored reserves and include proved, probable, and some possible gas. The data for Canada also include some probable reserves. The worldwide natural gas reserves have continued to increase as the demand for gas has increased and exploration efforts have expanded. In 1976, the world natural gas reserves were estimated to be 6.58 x 10. In 1987, the reserves were 1.06 x lO ", and by 1992... 

Unproved reserves are based on geologic and/or engineering data similar to that used in estimates of proved reserves but technical, contractual, economic, or rcgulatoiy uncertainties preclude such reseiwes being classified as proved. Unproved reserves may be further divided into two subcategories probable reserves and possible reserves. 

Probable reserves are those unproved reserves which analysis of geological and engineering data suggest are more likely than not to be recoverable. In this context, when probabilistic methods are used, there should be at least a. SO percent probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable reseiwes. 

Quantity with a probability of confirmation equal to or more than 90 per cent. Probable reserves... 

In the SPE/WPC scheme, reserves are classified according to the probability with which they can be produced into proved , probable and possible reserves. Under these definitions, proved reserves are those with a probability of at least 90% (P90) that the estimated volumes can be produced profitably proved plus probable reserves are required to have at least 50% probability (P50), while proved plus probable plus possible reserves are based on a probability of at least 10% (P10). 

Data compiled for 1992 placed the wodd s estimated proved natural gas reserves at approximately 1.24 x 1014 m3 (4.38 x 1015 ft3) (4). Data for the Confederation of Independent States (CIS) are denoted as explored reserves and include proved, probable, and some possible gas. The data for Canada also include some probable reserves. The woddwide natural gas reserves have continued to increase as the demand for gas has increased and exploration efforts have expanded. In 1976, the wodd natural gas reserves were estimated to be 6.58 x 1013 m3. In 1987, the reserves were 1.06 x 1014 m3, and by 1992 the reserve estimates had grown to 1.24 x 1014 m3. The distribution of the reserves in 1992 by principal geographical areas is shown in Table 1. In 1992, the principal political/geographical entities of the United States, the Confederation of Independent States (CIS), and the Oil Producing and Exporting Countries (OPEC) held 3.87, 39.97, and 39.7% of the wodd s natural gas reserves, respectively. 

Probable reserves are those reserves of petroleum that are nearly certain but about which a slight doubt exists. Possible reserves are those reserves of petroleum with an even greater degree of uncertainty about recovery but about which there is some information. An additional term potential reserves is also used on occasion these reserves are based upon geological information about... 

Probable reserves mineral reserves that are nearly certain but about which a slight doubt exists. 

Not included in reserves data are undiscovered but probably recoverable reserves in unexplored or unproven provinces. Currently, these probable reserves are estimated by the U.S. Department of Energy at 307-500 tcf, much of which almost certainly will become proven reserves when they become economically feasible. 

The certain reserves of chromite were estimated in 1975 to be 2.8 10 t, the probable reserves to be 5.4 10 t. Of the certain reserves 74% are in South Africa and 20% in Zimbabwe. In South Africa the reserves are so large that the mining companies have not bothered to determine them accurately. Exhau.stion of the reserves in the near future is not to be expected. Important extracting countries outside Southern Africa are (in alphabetical order) Albania, Brazil, Finland, the former States of the USSR, India, Iran, Madagascar, the Philippines and Turkey. Table 3.3-2 gives the chromite extraction figures for 1992. 

Should the probable reserves not be confirmed or be unusable for other reasons, a technology is available which solves the resource problem anyway, the fast breeder reactor. In fast breeder reactors the known uranium reserves would last for many hundreds of years, even in the event of a vast expansion in nuclear energy provision. 

Potential Reserves (Probable Reserves, Possible Reserves)... 

These reserves are the additional reserves of coal that are believed to exist in the earth. The data are estimated (usually from geological evidence) but have not been substantiated by any drilling or coring operations. Other terminologies such as probable reserves and possible reserves are also employed but fall into the subcategory of being unproven. 

The British government has been cautious about alleging direct contravention of the BWC, but has referred to activities which blur the distinction between BW and CW. According to a former senior Soviet specialist in the US Army, Apparently the Soviet Army considers biological weapons to be unsuited for tactical employment on the battlefield . He assumes from this that They are probably reserved for strategic employment deep in the enemy rear or in his homeland . No evidence is adduced for this assertion. It is equally likely that if the USSR is violating the BWC (which in terms of publicly available evidence is not proven), biological weapons are viewed as instruments of assassination or terror. 

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